Burglar alarm



Margh 23, i94s.-

' E. c. HEARD BURGLAR ALARM Fileddune 25; 1946 FIG. 2'.

FIG

INVENTOR EDWARD c.

HEARD ATTORNEY Fatented Mar. 23, 1948 UNITED STATES TENT OFFICE 2 Claims. 1

This invention relates to a burglar alarm and particularly to a noise-maker which is set off by the opening of a hinged closure.

One object of the invention is to provide an alarm which is inexpensive and simple in construction, installation, and maintenance. Another object is to provide a simple alarm means which makes a loud noise when released by movement of a closure such as a window or screen. Another object is to provide a simple alarm device which is not easily neutralized by an intruder without noise. These and other objects are attained by my invention which will be understood from the following description and the accompanying drawings in which: Fig. 1 is a front elevational view showing my alarm device as attached to a window frame adjacent a hinged screen frame; Fig. 2 is an enlarged front elevational view of the device; Fig. 3 is a side elevational view of the alarm device; Fig. 4 is a cross-sectional view taken on the line 4 l of Fig. 2.

Referring to the drawings, my device consists, in a preferred form, of a base plate I l which is provided with holes l2 for attachment by wood screws iii to a window or door frame W adjacent a hinged or laterally movable member, for example, a hinged screen frame S. Non-rotatably attached to the base plate H is a pivot member M to which is affixed the end of a coil spring i5 which is adapted to be wound spirally, around the central portion of the pivot. A cylindrical housing It is provided to enclose the helical spring l5, the other end of the spring being attached to the housing and the closed end of the cylindrical housing being attached to a striker arm I? on top thereof, which is adapted to rotate on the outer end of the pivot member 14, a head I? being provided to hold the striker and the cylinder for rotation on the pivot. The striker arm consists of two members arranged diametrically, each being provided with an upstanding headed pivot I9 upon which is loosely fitted a metal ring 28 which strikes the bell 2i asthe striker arm rotates on the pivot M. The helical spring :5 is wound up on the pivot member I l by hand turning of the striker arm until the spring is tight. The spring is prevented from unwinding by the holding of one of the striker arms against a portion of a window or door whose movement is coincident to the opening of the window or door. In Fig. 1, the device is shown on the vertical edge of a window casing between the window and the hinged screen frame S, the screen frame, when it is closed, acting to keep the striker arm from rotating. When the screen is opening by swinging outwardly, the striker arm is released and the tensioned spring l5 causes the striker arm to rotate rapidly, ringing the bell or other noise making element by the striking of the metal rings 20.

The advantages of my device are the ease of the application of the device to conventional window and screen combinations, as well as its mechanical simplicity which eliminates any possibilities of failure to act or to be set off, which is known to occur with more complicated alarm equipment. The device may be applied to other openings such as doors or gates so that the opening movement of the closure releases the strikers and a loud noise is created. The device is easily reset by hand-winding the spring and refastening of the screen frame or closure.

I claim:

1. In combination, a movable closure for a framed opening in a building, and a noise-making alarm device, said alarm device comprising a base member adapted to be attached to the framed opening adjacent said movable closure, a pivot mounted on said base, a spiral spring attached at one end to said pivot and to the other end to an enclosing casing, a casing adapted to enclose said spring and rotate on said pivot, a striker arm attached to said casing arranged to be held against rotation by contact with said closure, strikers pivotally mounted 0n the said arm and adapted to permit said arm to continue rotation after one of said strikers strikes a bell, and a bell attached to said base in position to be struck by said strikers, said striker arm being freed for rotation by said rotary means when said closure is moved from its striker arm holding position.

2. A noise-making alarm device comprising a base member adapted to be attached to the framed opening adjacent a movable closure, a pivot mounted on said base, a spiral spring attached at one end to said pivot and to the other end to an enclosing casing, a casing adapted to enclose said spring and rotate on said pivot, a striker arm attached to said casing arranged to be held against rotation by contact with a movable closure, strikers pivotally mounted on the said arm and adapted to permit said arm to cone tinue rotation after one of said strikers strikes a bell, and a bell attached to said base in position to be struck by said strikers.

EDWARD C. HEARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OBryan Mar. 25, 1913 

